An Iranian flag next to a ground-to-ground Sajil missile at an undisclosed location in Iran in 2008.
Photo credit should read -/AFP/Getty Images

Three US officials told The New York Times that intelligence photographs showing missiles being loaded onto boats by Iran's Revolutionary Guard Corps were behind escalating tensions between the US and Iran.

Other intelligence also hinted at plots by Iranian-backed militias to attack US troops and diplomats in Iraq, The Times said.

The intelligence is reportedly behind US decisions to enhance its military presence in the region and prompted the order to evacuate the US Embassy in Baghdad on Wednesday.

There is disagreement about the intelligence, however, with US, European, and Iraqi officials saying Iran may be acting defensively in reaction to a series of provocations by the US.

The May 3 overhead images showed fully assembled missiles being loaded onto boats in the Persian Gulf, three officials told The Times, raising concerns that they could be used by Iran's Revolutionary Guard Corps to target US Navy vessels.

Other intelligence reportedly hints at threats to commercial shipping vessels and to US troops in Iraq from Tehran-backed militias.

The intelligence was taken by the US's hawkish national security adviser, John Bolton, and Secretary of State Mike Pompeo to indicate that Iran might be preparing to attack US forces.

But others, including senior members of the Trump administration, senior European and Iraqi officials, and members of Congress reportedly believe that Iran's move to arm the ships may be a defensive response to provocations from Washington rather than a show of aggression.

Secretary of State Mike Pompeo flanked by the national security adviser, John Bolton, and the White House press secretary, Sarah Sanders. Associated Press

The intelligence prompted the White House to send Bolton to announce on May 6 that a US aircraft carrier and fleet of bombers would be sent to the Persian Gulf as a deterrent.

On Wednesday, Pompeo ordered the withdrawal of Americans from the US Embassy in Baghdad.

CNN first reported last week that intelligence showing Iran to be moving short-range ballistic missiles by boat was among the reasons prompting the US to increase its military presence in the Gulf.

According to the officials who spoke with The Times, Iran mobilized its forces because of US sanctions designed to stop nations from buying its oil and in response to the US's designation of the Guard as a terrorist group.